In the last issue of this magazine, I wrote about the plants that we use in our ponds. I mentioned the conflicts that might arise in the mind of somebody in choosing the plants that they might use in their plantings. Of course, there are always issues of culture to consider, but I also mentioned my concerns about the use of particularly invasive species, and the dangers that they pose to our native wild lands. These concerns are not to be taken lightly in my opinion, and I intend to expand on them in subsequent issues. This time, however, I want to talk about the animals that we keep.
In my work maintaining other peoples’ ponds for the past many years, I have come up against a particular phenomenon among pond keepers. That is that many of them want to keep too many things in their pond. Some people want too many koi. Others want too many turtles. Some actually want to encourage birds to visit their ponds. And the rest just want too many species in their ponds. Bio-diversity is nice, but even in the natural state a given pool might not support a large number of permanent residents. Any pond, including our own domestic ones, can support several species of visitors, such as coyotes, or raccoons, damaging as they can be, but keeping some animals, or combinations of animals, is a completely different matter.
This point has been driven home to me in the past couple of years because of a particular group of ponds that I maintain. All of the ponds are on the same property. The so-called, “main pond,” holds approximately 238,000-gal, while the other three hold considerably less. For many years, under the original owners, these ponds existed in a sort of isolated bliss, rarely suffering visits from any wild waterfowl, and the 50 large koi existed in harmony with several thousand Variatus Platies and Leucania goodei. I did see an Osprey come through one day, and saw it strike for a fish, missed, and fly away in a spectacular explosion of water and feathers. The pond was the quintessence of a well-balanced pond, and it was possible to see objects at the bottom of 6´ of water. Waterlilies flourished, and I was able to harvest Elodea and Ceratophyllum by the boatload, much to my profit. Then the house changed hands and it was not too long after the new owner moved in that he allowed his girlfriend to talk him into introducing swans to the pond. I emphatically advised against it, adding that swans look good on Christmas cards or in somebody else’s lake, but not in a domestic pond that is the centerpiece of the garden. I included warnings about the accumulation of feces, feathers, plant fragments, and other signs of stupid, unwitting damage done to the garden. I was ignored completely.
The swans were introduced in the spring of 2007, and have since turned the pond into the approximately 238,000-gal cesspool that was predicted. The lilies are mostly gone. The few that survive have been saved only by the depth of the water. The Elodea and Ceratophyllum are long gone, and the water is a swirling mess of algae, suspended material, feathers, and assorted plant fragments.
To make matters worse, a large cohort of Mallards that normally occupy the pond at the local tennis club have moved in, undoubtedly on the recommendation of birds that had stumbled upon the jackpot that is my client’s pond. There are plants to eat, food is set out in dishes, and the dog is an imbecile. I have seen as many as 63 ducks on the water at one time.
Instead of harvesting plants, and tending lilies, I now scoop out, by the net full, the substrate that had accumulated over the preceding decade, and which was stable with its populations of Nymphaea, Ceratophyllum and Elodea, along with a considerable percentage of fresh swan feces. The only true beneficiaries of this mess are the birds in the pond and the earthworms in my compost pile.
Many people have an intense desire to keep anything and everything that comes to hand or to mind in their ponds. This might stem from childhood memories of all of the things that they heard or saw “down in the creek,” or “crick.” They want to recreate some sort of vision that they might have harbored for decades. It is sometimes difficult to talk them out of their dreams, but it is often necessary because their expectations are so unrealistic. They expect to be able to keep one or two of everything, and that it will all work out somehow because they have a filter. Very few of them think about how all of these things will get along, now and over the seasons, or how one organism’s waste or habits will make life difficult for other species by polluting the water or by being overly territorial, and about how the more that you add to a pond, the more difficult the maintenance becomes.
I always tell people that if the book that you are referring to for information, or the guy who built the pond, tells you that your pond will support 10 fish, stop at 6. The closer you get to the full load, the more involved the maintenance becomes. Many of the calculations of how many fish will fit in a pond, or how much surface area should be covered with plants, etc., are attempts to formulize the things that affect water systems. Errors creep in because they are based upon what happens in a pond built in a certain way, set in a certain way, and supplied with the same amounts of food, etc. I tell people not be in a hurry to fill the pond with fish and other creatures. I tell them that they should be very discriminating in how they choose their fish. The pond will do far better if they exercise a bit of patience and try not to stick to a strictly formulaic approach.
Turtles are always popular, in spite of their propensity for destroying water plants. In fact, the inclusion of turtles is usually ill advised for anybody who wants a nice water garden. That same client of mine, seeking to entertain his children, put turtles into what were two nice ponds, with lilies and hawthorns as the main plantings.
One day I noticed a lot of detached leaves floating around, with their stems cut off somewhere near the bottom. I let this continue for a week or so just to see if it was a fluke, but I found myself removing more of the cut off leaves with each visit. In frustration, I poked around in the ponds until I found the culprits, two red-eared sliders. I removed them and the plants grew back. The client has never asked about them, and I haven’t told him. He is comfortable in thinking that they are there, and that is good, even though he has not seen them since he introduced them to the pond. Of course, now the swans have discovered the ponds (but not until the Hawthorns had grown back), with predictable results.
Another phenomenon is that many fishermen want to keep things that they bring home from the river or lake where they fish. Often, their catch includes crayfish or wild caught fish. Introducing crayfish to a decorative pond is to doom any potted plant. I have had several clients commit this colossal blunder. The problems arise when the crayfish begin to burrow into pots or embankments. In the case of pots, they loosen all of the soil from the plants’ roots, which allows it to escape the pot, leading to diminished water quality and a starved waterlily. In the case of mud embankments, their tunnels introduce water to places where it was never able to get before the crayfish made it possible, which accelerates erosion. Much in the same way that erosion along the gulf coast has been accelerated by incursions into the coastal marshes, which allows water into these areas, which facilitates their loss to the gulf.
Adding wild fish to the pond is dangerous because it is possible to introduce diseases and/or parasites to your domestic fish population. Also, most of them are game fish and want more room than can be offered in an average domestic pond. Some of these fish make nice additions to large ponds. Their habit of making a depression in the substrate for spawning can cause them to dig in large lily containers. I have gotten around this problem by offering them a tray of sand that is placed near the lily so that they still get the coverage from the lily, but they do not have to dig in the tray of lilies.
The use of fish that are too large for the pond is a problem as well. I once maintained a pond in which the lady of the house insisted on keeping about 50 huge Channel Catfish (Ictaluris punctatus). Her opinion was that they cleaned the bottom of the pond. It was obvious that they did not, because there was a lot of sediment in the pond when we began to care for it, and even though I pointed to the damage that they did to the lilies that she claimed to want, she would not part with the fish.
I learned to work with them over time, but the process was not particularly good for the pond. The fish lumbered around, swirling the silt on the bottom of the pond up into the water column, making it impossible to see into the water. They also dug the lilies up, creating an awful mess on at least one occasion. The pond was easily large enough to support a few catfish, but not one of that size. The system was not designed to keep up with such a load. Why have 50 fish that you cannot see, when you can have 12 that you can.
Another animal that might not raise eyebrows in some parts of the country, but certainly does with me, is the Bullfrog (Rana catesbeiana). In the good old days, before our local amphibians were threatened with this monster, the desert kept bullfrogs far to the east of here. But, here again, people from elsewhere have wanted to hear the familiar sound of bullfrogs in their yards, and have taken advantage of the easy supply that comes with feeder goldfish from Arkansas. They are collected by the hundreds with small goldfish and are not all culled out. The tadpoles come in with the goldfish, and are sold separately by the stores, or worse, given away to anybody that wants them. As a result, we have what I consider to be a problem that extends all the way up the pacific coast. A few years ago, I saw what looked very much like bullfrog tadpoles near Gig Harbor, Washington. I am sure that they have something to do with the demise of our local toad population.
So what should you include in your collection? There are many things that can be kept, actually. And there is nothing wrong with some of the ones mentioned above, if that is what you plan for. I don’t think that I would ever set a pond up to keep swans or crayfish, but they are, evidently, appealing to somebody, and it is possible to set up a situation in which they can live acceptably. I have seen many ponds that were set up for turtles, or to keep bass and bluegill to catch and release, or to keep large numbers of koi, and as long as the owners stay within the limitations of their systems, they have no problems. Whatever your purpose, though, merely putting a pond in the ground and filling it with disparate and incompatible species is irresponsible and can be a recipe for disaster.
I prefer to keep my ponds as simple as possible. I plant them extensively, since that is the true focus of my interests, and I stock them with large numbers of small, inoffensive fish, including Platies (P. variatus), Paradise Fish (Macropodus opercularis), Florida Blue-fin Killiefish (Leucania goodei), and Persian Killiefish (Aphanius mento), among others. I will of, of course, introduce goldfish and koi if the customer wants them, but I am not a fan of the carp, frankly, and so I am always pleased to hear somebody say that they do not want them. Sometimes it is just because they do not want to feed the local Heron and Egret populations, but whatever the reason, I like to hear it because of what it means as far as what I can include in the plantings.
All of these fish are compatible, although in the case of Macropodus, if they are kept with Aphanius or Leucania, it is good to separate a pair or two each spring and to spawn them in a safe tank to ensure the survival of the fry.
To keep it simple, I have never willingly introduced a Red-eared Slider to any pond, although I will tolerate those that arrive in certain ponds from the surrounding neighborhood, since this native of the American southeast has become feral in San Diego and there is nothing that I can do about it. Somehow, I still can’t dispatch a turtle the way I can a tadpole.
Ultimately, what a person chooses to keep in a pond will depend in large measure upon what the climate is like in their area. In areas in which I have never lived, native turtles, snakes, and other animals move into the ponds at will, and there is nothing that the pond owner can, or in many instances, should, do about it. These animals were there first in most cases, and to try to exclude them from what appears to them to be a natural habitat is rude. The more damaging ones should be kept at bay for practical reasons, but smaller animals that do no real harm should be allowed in.
We set these ponds up to bring a slice of the wetlands into our lives, so we shouldn’t be too surprised when a bit of the wetlands comes to our ponds. As it is with everything else in life, a balance must be struck between what we can tolerate and what we desire, and to find that balance in what we deliberately bring into our gardens is a goal that should not be dismissed out of hand.
About the Author
He is also the current President of the Southern California Water Garden Society.